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[PATCH] x86: fix small LDT allocation for Xen

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While commit 37868fe113 ("x86/ldt: Make modify_ldt synchronous") added
a nice comment explaining that Xen needs page-aligned whole page chunks
for guest descriptor tables, it then nevertheless used kzalloc() on the
small size path. As I'm unaware of guarantees for kmalloc(PAGE_SIZE, )
to return page-aligned memory blocks, I believe this needs to be
switched back to __get_free_page().

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/kernel/ldt.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- 4.2/arch/x86/kernel/ldt.c
+++ 4.2-x86-LDT-alloc/arch/x86/kernel/ldt.c
@@ -58,7 +58,7 @@ static struct ldt_struct *alloc_ldt_stru
 	if (alloc_size > PAGE_SIZE)
 		new_ldt->entries = vzalloc(alloc_size);
 	else
-		new_ldt->entries = kzalloc(PAGE_SIZE, GFP_KERNEL);
+		new_ldt->entries = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
 
 	if (!new_ldt->entries) {
 		kfree(new_ldt);



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[PATCH] x86: fix small LDT allocation for Xen "Jan Beulich" <JBeulich@suse.com> - 2015-09-01 12:50 +0200
  Re: [PATCH] x86: fix small LDT allocation for Xen Andy Lutomirski <luto@amacapital.net> - 2015-09-01 21:40 +0200
    Re: [PATCH] x86: fix small LDT allocation for Xen "Jan Beulich" <JBeulich@suse.com> - 2015-09-02 09:00 +0200

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